1. Field of the Invention
This invention relates to cable connector configurations, and particularly to a configuration for an optical fiber cable connector system.
2. Discussion of the Known Art
U.S. Pat. No. 5,455,880 (Oct. 3, 1995) discloses an optical fiber cable connector that can be used with polymer coated, glass optical fibers. The patented connector includes a connector plug having an axial bore, and a crimp ring also having an axial bore with a large diameter portion and a small diameter portion. A sleeve on the crimp ring forms the small diameter portion of the bore in the ring, and the sleeve is dimensioned to be received in the bore in the connector plug at one (proximal) end of the plug.
An optical fiber cable having an outer jacket, a clad core and an intermediate buffer layer, is partially stripped at one end of the cable to define a jacketed segment and an unjacketed segment. The stripped end of the cable is inserted through the large diameter portion and then through the small diameter portion of the crimp ring bore until the jacketed segment is disposed substantially within the large diameter portion, and the unjacketed segment projects out from the reduced diameter portion by a predetermined length.
The crimp ring is secured to the optical fiber cable by crimping its sleeve onto the unjacketed cable segment, and the unjacketed segment is inserted in the bore in the connector plug at the proximal end of the plug. A length of the unjacketed segment extends from the plug bore at the opposite (distal) end of the plug once the sleeve of the crimp ring is received in the proximal end of the plug. An annular flange on the crimp ring which surrounds the proximal end of the plug is then crimped to secure the ring to the plug. Finally, the length of the unjacketed cable segment extending from the distal end of the plug is cleaved, and the connector is ready for insertion into another, mating connector.
It will be appreciated that the connector of the '880 patent requires two distinct crimping operations for assembly with an optical fiber cable. The first crimp operation is performed on the crimp ring sleeve in order to secure the ring to the unjacketed segment of the cable, and the second crimp operation is performed on the annular crimp ring flange in order to fix the ring to the plug connector. Any forces tending to pull the stripped end of the cable out of the assembled connector will therefore be directed primarily through the unjacketed (i.e., reduced diameter) segment of the cable to the crimped sleeve of the ring. Thus, the connector may not be well suited for use in harsh environments where cable stresses combined with extreme temperature variations may result in a withdrawal or “pistoning” of a terminated cable with respect to the connector.
U.S. Pat. No. 5,923,805 (Jul. 13, 1999) relates to a connector for terminating a fiber cable having a plastics core, e.g., a polymethylmethacrylate (PMMA) core whose diameter is about 1.0 millimeter (mm) with a fluoropolymer cladding of less than about 25 microns (μm) thickness. The fiber is typically jacketed with a protective, opaque material such as a 0.5 mm thick layer of nylon. The connector includes a housing in which a metallic guide tube is retained, and a prepared end portion of the cable including the cable jacket is inserted through the guide tube. The guide tube is crimped about the cable to restrain cable from withdrawing from the connector housing when tensile forces are applied to the cable.
There is currently a strong demand for plastics optical fiber cables, particularly by the automotive industry wherein various standard and accessory automotive equipment are being adapted to cooperate with one another through a multimedia fiber-optic network. Known as Media Oriented Systems Transport or “MOST”, the network is optimized for automotive applications. Presently, about 20 international car manufacturers and more than 50 key component suppliers are adopting and working to implement MOST technology.
The configuration of the MOST network features relatively low cost interfaces for common devices such as microphones and speakers. At the same time, it allows more intelligent devices like integrated cellular telephones, digital radio receivers, GPS navigation modules, security systems, CD changers, voice recognition and activation systems, video displays and the like, each to determine those features and functions provided by all other devices that are coupled to the network. Control mechanisms may thus be established to eliminate unnecessary distractions should various subsystems seek to communicate with the driver of a MOST equipped vehicle. See generally, Internet web site <www.mostcooperation.com>.
The MOST standard specifies geometrical form factors for interfaces between a plug or “nose” of an optical fiber cable connector and a mating connector, without regard to a specific type of optical fiber carried by an associated cable. See MOST Specification Of Physical Layer, Rev 1.0 (February 2001) at pages 17-18, which may be downloaded through the above mentioned web site and is incorporated by reference.
Current MOST networks typically use an all plastics optical fiber cable with a 1000 μm diameter core for data transmission. But developing automotive applications are expected to surpass the optical bandwidth and environmental limitations of plastics core optical fibers, however. Accordingly, a polymer clad, pure silica core optical fiber such as, e.g., HCS® fiber available from OFS Fitel, is a valuable substitute for plastics core fiber and will satisfy future optical and environmental requirements for MOST networks. A connector system capable of providing a reliable interface for either polymer clad/silica core or all-plastics optical fiber cables, and which will satisfy present and future bandwidth and environmental requirements of MOST and other emerging fiber-optic networks, is therefore highly desirable.